There are numerous commercial applications for polymeric beads such as, for example, biological uses, medical uses, and industrial uses. Applications for polymeric beads continue to increase and expand in scope. There is a continuing need for polymeric beads with unique physical properties, chemical properties, and added versatility. Various methods are known for making polymeric beads. In most of the methods, droplets of polymerizable materials are reacted to form polymeric beads that are essentially spherical.
For example, emulsion polymerization methods are well known for making polymeric beads. Droplets of polymerizable materials in an oil or water emulsion are reacted to form polymeric beads. Although these methods work well, the resulting polymeric beads are often porous. Additionally, a thorough cleaning of the resulting polymeric beads is often needed to remove residual non-polymerizable materials such as oils and emulsifiers. In many cases, this cleaning often removes only the surface contamination but does not remove oils or other compounds that may be entrained within the polymeric beads. Although the polymerizable materials are often heated to initiate the polymerization reactions, radiation can also be used.
In another example, droplets of a polymerizable material can be formed that are allowed to fall under the force of gravity. The falling droplets can be subjected to radiation to initiate polymerization. Polymerization occurs as the droplets fall resulting in the formation of polymeric beads. Alternatively, the polymerizable materials can be subjected to radiation prior to the formation of the droplets but polymerization continues as the droplets fall resulting in the formation of polymeric beads.